package sword_offer;

import java.util.Deque;
import java.util.LinkedList;
import java.util.Stack;

/**
 * @ClassName _09BuildQueueWithTwoStack
 * @Description: 用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的功能。(若队列中没有元素，deleteHead 操作返回 -1 )
 * @Author: yongliang.ma
 * @Create_time:2022/10/10 13:17
 */
public class _09BuildQueueWithTwoStack {

    public class CQueue{
        private Deque<Integer> stackA = null;

        private Deque<Integer> stackB = null;

        public CQueue() {
            stackA = new LinkedList<Integer>();
            stackB = new LinkedList<Integer>();
        }

        public void appendTail(int value) {
            stackA.push(value);
        }

        public int deleteHead() {
            if (stackB.isEmpty()){
                while (!stackA.isEmpty()){
                    stackB.push(stackA.pop());
                }
                if (stackB.isEmpty())
                    return -1;
            }


            return stackB.pop();
        }
    }


}
